Abstract

Water is an important medium of any ecosystem in the world, both in qualitative and quantitative terms. Reduced water quantity and deteriorated water quality both have serious negative impacts on ecosystems. The water quality of running water ecosystems is determined by the geology, climate, and human activities in the drainage basin. Running water ecosystems have complex food webs that are adapted to local conditions. In order to protect and maintain natural populations of most large freshwater species, which frequently have important commercial value, we must ensure the integrity of the natural food web to which those populations belong. Nowadays, human population has explode tremendously with over six billion inhabitants on earth. It is anticipated that water shortages will involve countries that face rapid growing populations, mainly in Africa, Middle East, South Asia and South America including Malaysia. By the end of the decade, population growth and escalating per capita demand will severely squeeze water resources in many countries already facing shortages. At the same time, the quality of the water sources is being degraded at a rapid rate. More than 97% of the earth’s water is ocean, the next largest compartment is in the form of the ice caps and glaciers which account for another 2% though both are generally unsuitable for human use because of the salinity of seawater and location of ice caps and glaciers. Only 0.01% of the earth’s water can be used by humans for daily consumption in the form of freshwater. Is incorporates lakes and rivers, which are the main features for freshwater ecosystems. Freshwater ecosystems encompass water bodies together with their associated flora and fauna. Each of these are connected to a greater ecological and hydrological landscape that includes riparian areas, upland terrestrial ecosystems, and underlying groundwater aquifers.